1. Exemplary Field
The preferred embodiments of the present invention relate to, for example, apparatuses for managing operation of refrigerating machines. In some particular examples, the preferred embodiments relate to apparatuses for managing operation of refrigerating machines, the apparatuses controlling defrosting periods of a plurality of cooling/heating devices, such as showcases, refrigerators, freezers, or air conditioners, so as to prevent electric power from exceeding a predetermined maximum demand, the cooling/heating devices being installed in a store such as a supermarket and having refrigeration cycles formed therefor.
2. Description of the Related Art
In a store such as a supermarket, operation states of a plurality of cooling/heating devices, such as showcases or air conditioners, that are installed in the store and that have refrigeration cycles are centrally controlled by an apparatus for managing operation of refrigerating machines. Each of the refrigeration cycles is, typically, a cycle formed by connecting a compressor, a condenser, a decompressor, and an evaporator in a loop. When frost is deposited on the evaporator in a case in which a cooling operation is performed, the cooling efficiency decreases because the thermal conductivity of frost is low. In a case of an air conditioner, when the cooling operation is performed, the air conditioner is used in a state in which the evaporator thereof is at a temperature of about 15° C. Accordingly, the temperature of the evaporator of the cooling/heating device is higher than the temperature of the evaporator of a refrigerating apparatus or a freezing apparatus, and the frequency of deposition of frost is low. However, when a heating operation is performed, the air conditioner may be used in a state in which the evaporator thereof is at a temperature of 0° C. or lower. Accordingly, frost may be deposited on the evaporator.
In the related art, in a case of defrosting a plurality of cooling/heating devices, the cooling/heating devices are grouped into groups, and a time at which defrosting is performed is controlled for each of the groups (for example, see Japanese Unexamined Patent Application Publication No. 2008-111625). Because the cooling/heating devices are grouped into groups as described above, a defrosting period and a defrosting cycle may be set for each of the groups. The effort can be reduced, compared with that in a case in which the defrosting period and the defrosting cycle are set for each of the cooling/heating devices.
However, in defrosting control disclosed in Japanese Unexamined Patent Application Publication No. 2008-111625, the power consumptions of showcases, which serve as cooling/heating devices, during a recovery operation (a pull-down operation) of cooling the inside of the showcases again after defrosting is performed are not considered. For example, in a case of a store for which an upper limit value of the power consumption of the store is set by an electric power company, when increases in the power consumptions during the pull-down operation and an increase in the power consumption caused by the operation of the store coincide with each other, the sum of the power consumptions may exceed the set upper limit value.